Accumulating clinical research in animals and humans suggests that high amounts of abdominal fat, particularly within and around the organs inside the abdomen (visceral fat and liver fat), plays a crucial role in risk for diabetes and cardiovascular diseases. However, there have been no large epidemiologic studies examining the role of lifestyle on these abdominal fat stores. Until now, few, if any, epidemiologic cohort studies have included detailed measures of intra-abdominal fat depots from a large sample of community- based participants. The study proposed in this application uses an existing NHLBI dataset to fill these evidence gaps in a series of rigorous analyses. The NHLBI Coronary Artery Risk Development in Young Adults (CARDIA) Study includes detailed assessments of dietary and sedentary behaviors, as well as four abdominal fat depots (subcutaneous, visceral, intramuscular, and hepatic) assessed by computed tomography imaging in 3,170 African American and Caucasian adults that have been followed for 25 years in four U.S. metropolitan regions. The data set also provides a rich array of demographic and psychosocial factors that can be assessed as potential confounding factors. We propose to address the following three specific aims through analyses of CARDIA data in adult African American and Caucasian men and women: 1) Describe the associations between sedentary lifestyle habits and intra-abdominal fat depots. 2) Describe the associations between dietary patterns and hepatic fat. 3) Develop a prediction model for visceral fat volume based upon a combination of common clinical measures for use in research and translation to clinical practice. These analyses will lay the foundation for several areas of future research that we will propose to NIH in future applications, including prospective studies and community-based intervention studies. Such translational research geared towards changing lifestyle with the goal of improving body composition will be crucial towards scientific and public health progress in primary and secondary prevention of chronic diseases.